Estimated prevalence and incidence of hypersensitivity pneumonitis in Japan
August 20, 2024
Abstract
Background: The latest guidelines on hypersensitivity pneumonitis (HP) categorise the disease as either
fibrotic or non-fibrotic because of the greater clinical utility of this stratification. However, the prevalence
and incidence of fibrotic and non-fibrotic HP are unknown. This study assessed the exact prevalence and
incidence of fibrotic and non-fibrotic HP in Japan in 2021.
Methods: For adults, the study hospitals were selected by stratified random sampling according to
numbers of beds. The sampling rate was set at about 20%. The questionnaire survey was submitted to the
target hospitals. For pediatric cases, a survey was distributed to all members of the Japanese Society of
Pediatric Pulmonology and Japanese Society of Pediatric Allergy and Clinical Immunology.
Results: Regarding adult cases, in total, 575 facilities responded to the survey, resulting in a response rate
of 36.4%. The estimated prevalence and incidence of fibrotic HP were 6.3 and 2.5 per 100,000 population,
respectively, versus 3.6 and 2.0 per 100,000 population, respectively, for non-fibrotic HP. Both fibrotic
and non-fibrotic HP were more prevalent in southern Japan (Kyushu) and less prevalent in northern
Japan (Hokkaido). The incidence of non-fibrotic HP was significantly lower in December than in the other
months (relative risk ratio ¼ 0.36, p < 0.001). Three cases of fibrotic HP and five cases of non-fibrotic HP
were identified in children.
Conclusions: This study determined the prevalence and incidence of fibrotic and non-fibrotic HP in Japan
for the first time.
© 2024 Japanese Society of Allergology. Published by Elsevier B.V. This is an open access article under the
CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
fibrotic or non-fibrotic because of the greater clinical utility of this stratification. However, the prevalence
and incidence of fibrotic and non-fibrotic HP are unknown. This study assessed the exact prevalence and
incidence of fibrotic and non-fibrotic HP in Japan in 2021.
Methods: For adults, the study hospitals were selected by stratified random sampling according to
numbers of beds. The sampling rate was set at about 20%. The questionnaire survey was submitted to the
target hospitals. For pediatric cases, a survey was distributed to all members of the Japanese Society of
Pediatric Pulmonology and Japanese Society of Pediatric Allergy and Clinical Immunology.
Results: Regarding adult cases, in total, 575 facilities responded to the survey, resulting in a response rate
of 36.4%. The estimated prevalence and incidence of fibrotic HP were 6.3 and 2.5 per 100,000 population,
respectively, versus 3.6 and 2.0 per 100,000 population, respectively, for non-fibrotic HP. Both fibrotic
and non-fibrotic HP were more prevalent in southern Japan (Kyushu) and less prevalent in northern
Japan (Hokkaido). The incidence of non-fibrotic HP was significantly lower in December than in the other
months (relative risk ratio ¼ 0.36, p < 0.001). Three cases of fibrotic HP and five cases of non-fibrotic HP
were identified in children.
Conclusions: This study determined the prevalence and incidence of fibrotic and non-fibrotic HP in Japan
for the first time.
© 2024 Japanese Society of Allergology. Published by Elsevier B.V. This is an open access article under the
CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Journal Article
JOURNAL： Allergology International
TITLE： Estimated prevalence and incidence of hypersensitivity pneumonitis in Japan
Correspondence to
Miyazaki Yasunari, Professor
Department of Respiratory Medicine,
Graduate School of Medical and Dental Sciences,
Tokyo Medical and Dental University(TMDU)
E-mail: miyazaki.pilm(at)tmd.ac.jp
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